A 9-Connected Zirconium-Based Metal-Organic Framework for Ammonia Capture

Construction of multifunctional metal-organic frameworks (MOFs) with asymmetric connectivity have the potential to expand the scope of their utilization. Herein, we report a robust 9-connected microporous Zr-based MOF, NU-300, assembled from asymmetric tri-carboxylate ligands and Zr₆ nodes. As indicated by single-crystal X-ray diffraction analysis, there exist uncoordinated carboxylate groups in the structure of NU-300 that can participate in ammonia (NH₃) sorption through acid-base interactions which yield high uptake of NH₃ at low pressure regions (<0.01 bar). In situ infrared (IR) spectroscopy shows the interactions between Brønsted acidic sites and NH₃, which suggests that NU-300 can be used as a sorbent for NH₃ capture at low pressures.